CHEMISTRY COMMUNITY

Morgan Micallef 1A

In this case, when you subtract ln[A]o from both sides of the equation ln[A]=-kt+ln[A]o, you get ln[A]-ln[A]o=-kt. One of the fundamental log properties is that lnx-lny=ln(x/y), so you would get the final equation ln [A]/[A]o = -kt using this property

Morgan Micallef 1A

In the solutions for the Achieve assignment it said somewhere that catalysts are consumed and then produced, while intermediates are produced and then consumed

Morgan Micallef 1A

I would definitely focus your studying primarily on thermodynamics and kinetics!

Morgan Micallef 1A

I generally use seconds in the equation and then convert to whatever units the question is asking for afterward

Morgan Micallef 1A

The rate of the reaction should be expressed as a positive value!

Morgan Micallef 1A

Since catalysts are enzymes, they have a specific range where they function most efficiently and denature once they reach a certain higher temperature.

Morgan Micallef 1A

Just replace the units with the position of the variable and cancel out on both side: Rate = mol/L*s []= mol/L zero: Rate = k[A] 0 mol/L*s = k first: Rate = k[A] 1 mol/L*s = k (mol/L) 1/s or s -1 = k second: Rate = k[A] 2 mol/L*s = k (mol/L)(mol/L) **this one was a little harder to do but if you cr...

Morgan Micallef 1A

Hello! So a catalyst will decrease the activation energy and increase the rate of the forward reaction. The same applies to the reverse reaction. The overall reaction remains the same with the addition of a catalyst, it is the mechanism (or path taken) that changes. Delta H is a state function, so i...

Morgan Micallef 1A

Don't worry, all it was saying is that 2/5 of your posts for this week have to answer questions so that you aren't just asking 5 questions!

Morgan Micallef 1A

Hello! I'm assuming it will be very similar to the 14A final, which had questions from all of the outlines

Morgan Micallef 1A

The rate law tells us that A is first order and B is second order, so [A]=(1/2)^1=1/2 and [B]=3^2=9. You then multiply 0.0840*(1/2)*9 to get your final answer. You can apply the same technique to the second half of the problem.

Morgan Micallef 1A

Hello! You will be able to find it if you scroll down on the homepage of Lavelle's 14B website :)

Morgan Micallef 1A

Using the rules that others have posted in the comments, you can determine what the oxidation numbers of other molecules in a compound are to give the overall charge of the compound

Morgan Micallef 1A

Thermodynamics tells us about whether a reaction is likely to occur, while kinetics tells us how fast a reaction will occur

Morgan Micallef 1A

Adding a catalyst lowers the activation energy for both the forward and reverse reactions

Morgan Micallef 1A

Hello! The intergrated equation for a zero-order reaction is A=-kt+A0. According to this equation, the slope of the line is -k

Morgan Micallef 1A

Hello! Yes, the equation only works in Kelvin. The conversion is Kelvin=Celsius+273.15

Morgan Micallef 1A

The graph ln[A] vs. time should have a linear downward slope. The slope should be -k

Morgan Micallef 1A

I've found the content to be more difficult but also way more interesting so I've been doing better this quarter than in 14A

Morgan Micallef 1A

Hello! So spontaneity doesn't tell us about the speed of the reaction, only how likely it is to occur by itself, so fast doesn't equal spontaneous

Morgan Micallef 1A

My thinking is that since the units for rate is always M/s (or m/L*s), what units for k do I need so that everything cancels out to M/s? For example, the rate equation is rate=k, so for that, the units of k would be M/s. For the 1st order, the equation is rate=k[A], so we know that k has to have se...

Morgan Micallef 1A

Delta H is referring to the change of heat in a system. A negative delta H means the system is losing heat, and a positive delta H means that the system is gaining heat

Morgan Micallef 1A

All of the values listed are state functions

Morgan Micallef 1A

The anode (-) is on the left side and is the half of the reaction being oxidized, the cathode (+) is on the right side and is the half being reduced

Morgan Micallef 1A

For me, moving around throughout the day to different study spaces helps me stay focused and not fall asleep. But, it is really important to give yourself breaks! I know I can't go more than an hour and a half without a break, otherwise I end up getting absolutely nothing done.

Morgan Micallef 1A

Phoebe Bridgers, Jhene Aiko, Lucy Dacus, Daniel Caeser, and Dominic Fike are some of my favorites

Morgan Micallef 1A

Doing the assigned problems from the textbook is super helpful, especially since some of them show up on the exams! It also just helps you feel more prepared since you know what kinds of problems you are going to have to do

Morgan Micallef 1A

Definitely check out the Hammer museum! Also, Espresso Profeta is a nice study spot

Morgan Micallef 1A

You can take the bus to Santa Monica, or go to the Getty, or check out the Hammer museum!

Morgan Micallef 1A

I like to go for walks around campus!

Morgan Micallef 1A

There was a problem using degeneracy in the homework problems on the syllabus, and the first two learning outcomes on outline 4 had to do with this, but I don't know if we would be tested on it.

Morgan Micallef 1A

For the line diagram, Cl- is closest to the double lines on both sides. You don't need to include stoichiometric coefficients in the cell diagram, and the anode (oxidation half) goes on the left and the cathode (reduction half) goes on the right!

Morgan Micallef 1A

There is no work being done, so delta U is zero and so is q. Delta Ssurr=-q/T=0

Morgan Micallef 1A

The molecule being oxidized is losing electrons and giving them to the molecule being reduced, so it is acting as the reducing agent, and vice versa for oxidizing agent. Oxidized=Reducing agent, Reduced=Oxidizing agent

Morgan Micallef 1A

Once you separate the reaction into the reduction and oxidation halves, add H2O and OH- as necessary to balance it. Also, check out this document for help when balancing in basic conditions! https://lavelle.chem.ucla.edu/wp-content/supporting-files/Chem14B/Balancing_Redox_Reactions_Basic_Conditions....

Morgan Micallef 1A

In the cathode half of the reaction you need 2Ag!

Morgan Micallef 1A

Correct, the higher the standard reduction potential, the better the oxidizing agent

Morgan Micallef 1A

Your reactants in this case are Fe, O2, and H2O. To balance the products, any coefficient you put in front of the Fe will apply to both sides of the black circle

Morgan Micallef 1A

I don't know if you put that OH- was aqueous in your answer or not, but make sure to include the phases or achieve will mark it incorrect!

Morgan Micallef 1A

Q is the concentration of products over the concentration in reactants, in this problem it would be 0.824/0.0190M

Morgan Micallef 1A

Yes, you can use Gnaught=-nFEnaught to relate them

Morgan Micallef 1A

I was also really confused about this, since the cathode is on the right side of the electrode I figured it would be the product

Morgan Micallef 1A

The greater the number of atoms, the more positions they are capable of occupying, and the higher the entropy

Morgan Micallef 1A

For the Ag half of the reaction, all you need to do is add electrons to the more positive side to balance the charges. For the oxidation half, add OH- and H2O molecules to balance the equation

Morgan Micallef 1A

Hello! n is the number of electrons being transferred from the reduction half of the reaction to the oxidation half of the reaction. You can find n by balancing both halves of the redox reaction

Morgan Micallef 1A

Hello! The cell here is basically referring to the two halves of the reaction together, so the oxidation (anode) and reduction (cathode)

Morgan Micallef 1A

We are adding the electrons to show how much the charge of the oxidized/reduced molecule is changing. We also need to make sure that the charge is balanced between both half reactions

Morgan Micallef 1A

You can determine which one to subtract by calculating which way makes E positive!

Morgan Micallef 1A

You can use the Nernst equation, Ecell=Ecell naught-(RT/nF)lnQ

Morgan Micallef 1A

Hi! You first separate it into two half reactions, then use the chart to find the standard reduction potential of each half, then use delta G naught = -nFE to calculate the free energy change. In this case, n is the number of electrons transferred, which you can find using your half reactions

Morgan Micallef 1A

On the homework, there was a question about calculating the Kb for an amine, but I wasn't sure what an amine is. Could someone explain?

Morgan Micallef 1A

Could someone define what a monoprotic weak acid is? I wasn't sure what this meant on the homework

Morgan Micallef 1A

February 2nd! I hope it is announced whether its going to be online or not soon, but I would assume it's going to be in person

Morgan Micallef 1A

I was also confused about this! For weak acids, if pH is greater than pKa, there is more of the charged species; if pKa is greater than pH, there is more of the neutral species. For weak bases, the opposite is true.

Morgan Micallef 1A

I'm a little confused about when to use Kc vs Kp since Dr. Lavelle said we don't need to include solids or liquids when solving for the equilibrium constant?

Morgan Micallef 1A

Mine was really good! I got to see my dogs and my little brother :) I'm really excited to go back for winter break!

Morgan Micallef 1A

With this class, I try to spread out my studying as much as possible. I do one topic a day so I don't get too overwhelmed and try to do practice problems. Mostly just remember that chemistry is a difficult subject, and don't be afraid to ask for help when you need it!

Morgan Micallef 1A

once you draw the lewis structure, pay attention to where the dipole moments are pointing. If they're in opposite directions, they cancel out and the molecule is nonpolar

Morgan Micallef 1A

I believe the main angles we have to know are 180, 120, 109.5, and 90

Morgan Micallef 1A

Hahahah this is incredible thank you!!

Morgan Micallef 1A

VSEPR=valence shell electron pair repulsion theory, it tells us about the molecular geometry of a molecule based on the number of bonds and lone pairs

Morgan Micallef 1A

Kayla Ziebell 1H wrote:Anyone heard any good jokes about sodium . . .
Na

This actually made me laugh

Morgan Micallef 1A

what is the second-best public university's favorite element?
Berkelium

Morgan Micallef 1A

You should calculate the formal charge for each atom and determine which structure has the lowest overall formal charge

Morgan Micallef 1A

How is everyone planning on studying for the final these last couple days?

Morgan Micallef 1A

Will we need to know this on the final?

Morgan Micallef 1A

Yes, it's available for download on the chem 14a website!

Morgan Micallef 1A

Sigma bonds can rotate, pi bonds can't!

Morgan Micallef 1A

This is such a cool thread, thank you!!!

Morgan Micallef 1A

Currently, you get access to the E-textbook automatically because you need to access achieve to complete the homework assignments

Morgan Micallef 1A

The peer learning sessions are also super helpful if you can't get a private tutor!

Morgan Micallef 1A

Dr. Lavelle has been really understanding about this, starting each new section of the class (each outline) with a review of the topics you need to know from high school!

Morgan Micallef 1A

Thank you for starting this thread, everything here is super interesting!!

Morgan Micallef 1A

Thank you!!!

Morgan Micallef 1A

The way I usually do it is the "your posts" link under quick links

Morgan Micallef 1A

Thank you Dr. Lavelle!
It has been a great quarter even in an online class. I'm excited to get to attend lectures in person next quarter!

Morgan Micallef 1A

I'm pretty localized electrons stay associated with only one atom, while delocalized electrons are spread out throughout the molecule

Morgan Micallef 1A

I try to only go to the textbook when I'm really confused on a topic, otherwise, TAs are generally more helpful for specific questions. I also get stressed out by the language in the textbook

Morgan Micallef 1A

Thank you so much, this was really helpful to read!

Morgan Micallef 1A

So pi bonds only form when there are double and triple bonds forming?

Morgan Micallef 1A

Hi! I'm pretty confused about how you determine the type of hybridization that is occurring, could someone explain?

Morgan Micallef 1A

They are the same! H+ is just a simplified way to write H3O+

Morgan Micallef 1A

VSEPR charts are super helpful for determining shape based on the number of bonds and lone pairs!

Morgan Micallef 1A

Hi! When a base accepts a proton, it forms a conjugate acid, and when an acid donates a proton, it forms a conjugate base

Morgan Micallef 1A

Thank you for the explanations, can a base be both a lewis base and a bronsted base?

Morgan Micallef 1A

Thank you for the quizlet!

Morgan Micallef 1A

So it depends on both the charges of the ions and the strength of the positive or negative charges?

Morgan Micallef 1A

I was also confused about this, thank you for the explanations!

Morgan Micallef 1A

The more oxygen atoms there are, the more polar and more stable the compound is, making it a weak acid

Morgan Micallef 1A

as other people said, when the compound is covalent you draw lines for the bonds, but when it is ionic you draw the atoms separately with their charges indicated

Morgan Micallef 1A

I'm also really nervous about this final, I feel super unprepared because I haven't taken chemistry since sophomore year of high school

Morgan Micallef 1A

I usually try to finish my studying early the night before and don't do anymore the morning of the test, it only stresses me out more at that point. Eating a good breakfast the morning of the exam is super important!

Morgan Micallef 1A

Hello, I am a bit confused/overwhelmed with the achieve week 2,3,4. I have completed most with the exception of two problems I planned to go to an office hours to discuss over the course of this week. I went to office hours over the weekend and since the review sessions were midterm review, I was f...

Morgan Micallef 1A

I usually keep my full unrounded answers throughout the problem and state my final answer with the correct number of significant figures

Morgan Micallef 1A

I was confused about what this constant actually was too, could someone also explain what Planck's constant is?

Morgan Micallef 1A

If the wavelength is less that 10^-15 m it is too small to be detected, anything larger than this will be detectable in a lab

Morgan Micallef 1A

The speed of light is a constant, at least in this class! So yes we can always use 3.00x10^8

Morgan Micallef 1A

The two reagents are always present in a one to two ratio, so you have to multiply the amount of the limiting reactant by this ratio to determine how much of the excess reagent will be used

Morgan Micallef 1A

The molar mass of the compound remains the same, the coefficient just tells you that you have two moles of the substance

Morgan Micallef 1A

Thank you for sharing! I've been struggling to remember how to perform stoichiometry calculations and I was still a little confused about the molar ratio but this is super helpful for setting up the problems!

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